Citrus fruit juice drinks are widely enjoyed by many people. Unfortunately, citrus fruit have specific growing seasons, and grow only under certain climatic conditions, i.e., tropical and subtropical. Accordingly, citrus fruit are therefore available in fresh form for only a portion of the year. To have citrus fruit juice in good quality available year round and anywhere, the citrus fruit juice is typically processed for storage and distribution.
Since citrus fruit juice typically contains about 80 to 90% water, a common way to store and distribute the juice has been in the form of a concentrate, the bulk of which is a frozen concentrate. However, concentrating the juice may impair the quality of the juice, in that the volatile aroma and flavor compounds of the natural juice are reduced.
Alternately, the fresh citrus fruit juice may be frozen without any concentration. Here, relatively large containers, such as drums, are used or the juice is frozen in the form of large slabs or blocks. The size of these drums and slabs or blocks results in time-consuming freezing and thawing. In addition, large ice crystals are typically formed during the freezing. These large ice crystals typically rupture the sacs and cells if the pulp, and the ruptured sacs and cells are then diluted during the thawing.
When freezing in a conventional fashion, the temperature drops very slowly and several undesired bacterial and mold species can grow and multiply. Therefore, a pasteurisation is typically performed before freezing and is also performed upon thawing for safety reasons. This heat treatment causes degradation of the natural aroma level to a product with off-aroma and off-taste and browning of the juice and the pulp. Further deterioration of the quality of the juice is due to slow ice formation during freezing, resulting in oxidation and migration of water and sugar, such that the whole drum, slab or block of frozen juice must be thawed before further processing is possible.
Furthermore, thawing may take several days and may be subject to bacteriologic contamination and yeast fermentation. On the other hand, if the slabs or blocks are crushed in order to speed up the thawing, a high percentage of the juice sacs and other fruit cells will be mechanically ruptured or damaged and the juice quality will be severely decreased.